In the sex toy industry and generally in the field of sexual stimulation devices, reciprocating type devices are known. These sexual aids are design to improve the sexual experience for one or more participants and are known in the art. Such aids vary widely in the sex toy industry. Some other known devices use a cam turned by a motor to act on a reciprocating piece. Other devices use a push rod mounted to a disc or wheel driven to push and pull the rod generally along the reciprocating direction. Generally, the latter type device has the disadvantages that it is large and uses excessive amount of battery power to drive it to be of any benefit for the user. The cam type devices suffer from limited stroke length, an awkward shape to accommodate the rotating cam, a weak drive force in the portable versions, and an asymmetry in the ascending and descending stroke force.
Another type of device is described in U.S. Pat. No. 8,308,631 to Kobashikawa et al., which uses linear movement along a screw, and reverses the motor to reverse directions. While the present inventor is not aware if such a device is commercially available, the design as presented in the therein would suffer from speed, torque and control problems and limited battery power due to the in-efficiency of the drive mechanism, and would not generally have good life of the components due the constant need for lubrication along the screw. What is needed are reciprocating stimulation devices that offer improved stroke length, while allowing portability, battery power, and drive efficiency, and ability to drive various shapes and size of reciprocating stimulation bodies for use in various toys.